Proteolytic enzymes isolated from either bacteria or host tissues have previously been shown by others to act directly on soluble collagen or human C'5 resulting in the production of fragments chemotactically active toward neutrophils. Thus, it seems likely that mechanisms independent of antibody and/or complement exist for initiating inflammation. In the light of the above published observations, we propose to determine whether proteases isolated from selected oral bacteria (Streptococcus mutans, S. sanguis, Actinomyces viscosus, A. naeslundii, Fusobacterium nucleatum, Veillonella alcalescens and Candida albicans) are, in fact, capable of generating chemotactic fragments from (1) proteins derived from gingival sulcular bacteria, (2) non- chemotactic proteins found in gingival tissue such as serum albumin, elastin and soluble collagen, and (3) purified human C'5. Extra- and intra-cellular bacterial proteases will be purified by standard procedures and some of their relevant characteristics (MW, inhibitors, optimal assay condition) determined using a sensitive radioassay method. Rabbit neutrophil chemotaxis assays will be performed in the absence of serum in modified Boyden chambers. The results of this study will establish the role oral bacterial proteases play in the initiation of inflammation in the human gingiva.